My theory-
The previous settlement dies out for some reason- disease,changing climate,war or invasion.
The remaining people decamp.
The site falls in to disrepair, then nature takes over. Grass then trees take over, buildings collapse rot away. The dust and debris fall into foundations.
After years the landscape is back to natural, whatever caused this space to be habitable is appealing to next humans. They start the cycle over again.
Machu Pichu (sp) comes to mind, pull back the jungle- there is a city and lost civilization.
Wow. Great answer. Thanks. Makes sense.
There’s an unfinished highway on staten island. Would have made commuting life much easier but liberals shot it down because of the Greenbelt.
Thing is, some parts are already mostly covered in grass some 30 years later. Used to walk on it as a kid.